Conveyor ball unit

ABSTRACT

A conveyor ball unit comprises a conveyor ball resting on mounting balls in a mounting shell. A retaining ring is provided to hold the conveyor ball on the mounting balls in the mounting shell. The mounting shell can be set into an opening in a supporting structure and rests on the supporting structure by way of a shell rim. The unit is fixed in place by resilient first locking elements comprising in a first embodiment of the invention resiliently deformable projections which also define radial recesses in the interior of the mounting shell into which recesses projections formed on the retaining ring can be inserted in order to fix the ring within the mounting shell.

This is a divisional of U.S. patent application Ser. No. 882,412, filedMay 13, 1992 now U.S. Pat. No. 5,219,057.

FIELD OF THE INVENTION

The present invention relates to a conveyor ball unit in which aconveyor ball is mounted on mounting balls within a mounting shell.

DESCRIPTION OF THE PRIOR ART

Conveyor ball units of this kind are widely used to move containers orsimilar items in the loading areas of freight aircraft. It is evidentthat apparatus for this purpose must be light but robust. Furthermore,they should be simple in design to minimize their cost, and theirinstallation and replacement should involve no major expenditure oflabor.

In U.S. Pat. No. 1,963,956 a conveyor ball unit is described that isfixed to a support by screws so that an elaborate installation procedureis required.

German DE-PS 249 648 discloses a conveyor ball unit that comprises acast element and hence is very heavy.

A conveyor ball unit is described in German DE 35 07 945 C1 in which themounting shell is attached to a retaining ring and the retaining ring isattached to an additional ring-shaped holding element. The whole unit isthen set into an opening in a supporting structure. This unit is thuselaborate in construction. Another elaborately constructed unit isdisclosed in German DE 35 41 020 wherein the conveyor ball unit has amounting shell contained within a housing. The housing bears hook-shapedelements by which the conveyor ball unit is fixed in a supportingstructure.

In German DE 89 15 491 U1 a retaining ring of the conveyor ball unit isattached to a mounting shell by teeth. The mounting shell carries a boltthat must be adjusted at least when the conveyor ball unit is removedfrom the opening in the supporting structure. This arrangement is thusrelatively complicated, both in construction and in operation.

German DE 39 27 560 A1 discloses a conveyor ball unit in which aretaining ring has resilient bolts integral with the ring, which serveboth to hold the ring in the mounting shell and to hold the wholeconveyor ball unit in the supporting structure. To remove this conveyorball unit from the supporting structure is a relatively complicatedprocedure requiring some dexterity. Furthermore, as the retaining ringis retained relatively elastically in the mounting shell, when it is inuse the conveyor ball can move appreciably with respect to the mountingshell, so that the arrangement is subject to greater wear. Additionally,this unit is relatively complicated in structure.

SUMMARY OF THE INVENTION

The present invention is directed to the problem of developing aconveyor ball unit of the type described at the outset in such a waythat, while remaining simple in structure, it is more resistant to wearand at the same time can be more easily installed and removed thanconventional units.

According to a first aspect of the present invention there is provided aconveyor ball unit comprising a conveyor ball; a mounting shell for theconveyor ball; a plurality of mounting balls for supporting the conveyorball in the mounting shell; a retaining ring to keep the conveyor ballin position on the mounting balls within the mounting shell; a resilientfirst locking element for the attachment of the mounting shell to asupporting structure and for bracing a rim of the mounting shell againstthe supporting structure, the first locking element being formed by atleast one resiliently deformable projection on the mounting shell, whichresiliently deformable projection also defines a radial recess withinthe mounting shell; and a projection formed on the retaining ring, whichprojection is inserted into the radial recess to fix the retaining ringwithin the mounting shell.

It will be appreciated that in this embodiment of the invention themounting shell is positioned between the supporting structure and thesites on the retaining ring at which the latter is fixed to the mountingshell. This arrangement ensures that when the conveyor ball unit isseated in the supporting structure, the supporting structure itselfopposes movement of the retaining ring with respect to the mountingshell.

Alternatively, according to a second .aspect of the present inventionthere is provided a conveyor ball unit comprising a conveyor ball; amounting shell for the conveyor ball; a plurality of mounting balls forsupporting the conveyor ball in the mounting shell; a retaining ring tokeep the conveyor ball in position on the mounting balls within themounting and a first locking element which is inserted into an openingdefined by the mounting shell so that it partly projects beyond theouter surface defined by the mounting shell to attach the mounting shellto a supporting structure and to brace a rim of the mounting shellagainst the supporting structure, and which projects into a radialrecess defined by the retaining ring to fix the retaining ring withinthe mounting shell.

This second embodiment achieves the same advantages as described above.

In both cases, the first locking elements are preferably shaped so thatthe mounting shell can be releasably snapped fitted into an openingdefined by the supporting structure and held firmly, without need of anybolt or the like, and can be removed by releasing the snap engagement.Thus there is no need for an operator to acquire a particular skilldemanded by a special-purpose bolt arrangement.

Preferably also, at least one second locking element is provided andforms part of the mounting shell on the other side of the conveyor balldiametrically opposite said first locking element. Thus, with only aslight modification that preserves the robustness of the unit, secureseating is ensured.

Preferably also, the shell rim defines a slot adjacent to the firstlocking element, into which slot a tool can be inserted to lever theconveyor ball unit out of the opening defined by the supportingstructure. A suitable tool is the blade of a screwdriver and, asscrewdrivers are always at hand, it is a very simple operation to removethe unit.

Preferably also, a pair of the first locking elements are provided andthe slot is located between them. Thus the stability of the seating isincreased and, owing to the symmetry, the process of levering the unitout is simplified.

Preferably also, the mounting shell is formed from a sheet material anddefines a part-spherical portion in which the conveyor ball is mountedand a substantially horizontal portion running radially outwards fromsaid part-spherical portion towards said rim of the mounting shell, saidsubstantially horizontal portion being resiliently deformable so thatsaid part-spherical portion can be moved with respect to said rim. Thisflexibility can be achieved by an appropriate choice of material anddimensions. It will also be appreciated that this feature of theinvention ensures that the bearing is resilient to a certain degree, sothat even hard impacts upon the conveyor ball do not irreversibly deformthe mounting shell.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective cross section view of a supporting structure fora conveyor ball unit according to present invention;

FIG. 2 is a view of the supporting structure as shown in FIG. 1 in whichan opening has been made;

FIG. 3 is a plan view of a first embodiment of conveyor ball unitmounted in the supporting structure;

FIG. 4 is a side view of the conveyor ball unit shown in FIG. 3 in thedirection of a locking element;

FIG. 5 is a cross sectional view of the supporting structure with theupper opening shown in FIG. 2;

FIG. 6 is a side view of the conveyor ball unit shown in FIG. 3 showingthe opening;

FIG. 7 is a partial sectional view along the line VII--VII in FIG. 3;

FIG. 8 is a partial sectional view along the line VIII--VIII in FIG. 3;

FIGS. 9 to 12 are views of a second embodiment of the invention,corresponding to the views of the first embodiment shown in FIGS. 3 to 6respectively;

FIG. 13 is a sectional view along the line XIII--XIII in FIG. 9; and

FIG. 14 is a sectional view along the line XIV--XIV in FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description the same reference numbers are used foridentical components or those with an identical purpose in thedescriptions of both the first and the second embodiments.

FIG. 1 is a perspective cross sectional view of a supporting structure10 into which a conveyor ball unit according to the invention can beset. The supporting structure 10 can be manufactured as an extrudedprofile and comprises an upper surface 11 connected to a lower surface12 by vertical members. The upper surface 11 has integral reinforcingribs 15.

To enable a conveyor ball unit to be installed in the structure 10, ahole is first made in the upper surface 11. Then the circumference ofthe hole is milled, removing material of the upper surface 11 in such away that the reinforcing ribs 15 project into the resulting opening 14and form seating surfaces 16 on their upper sides.

A first embodiment of conveyor ball unit is shown in FIGS. 3 to 8. Itcomprises a conveyor ball 21 rotatably mounted in a mounting shell 23 bymeans of mounting balls 22. At its upper margin the mounting shell 23projects to define a substantially horizontal annular portion 25 whichis continuous with a vertical securing portion 35 and a substantiallyhorizontal shell rim 30. The outside diameter of the horizontal shellrim 30 corresponds to the diameter of the milled-out region which, aspreviously described, encircles the hole drilled in the surface 11 ofthe supporting structure 10 to form the upper opening 14.

The conveyor ball 21 is held within the mounting shell 23 by a retainingring 24. In the middle of the retaining ring 24 is a hole which, atleast in its upper part, has a diameter less than that of the ball 21.

The retaining ring 24 consists of a resilient material, preferably ofplastics, and has several projections 26, four in the embodimentillustrated here, with rounded contours. In regions corresponding to thepositions of the projections 26 in the retaining ring 24, there arecorrespondingly shaped recesses in the interior of the mounting shell23, which appear as rounded projections on the outer surface of themounting shell 23. These projections constitute first locking elements35. The mounting shell 23 is formed from a sheet of material of suitablethickness and elasticity, so that when a load is imposed on the conveyorball 21 the horizontal portion 25 can yield in accordance with the loadand thereby prevent transmission of very hard impacts from the conveyorball 21 to the mounting shell 23 by way of the mounting balls 22. Thiselasticity also allows the locking elements 35 with the enclosedprojections 26 to give way slightly in the radial direction.

In a region between two reinforcing ribs 15, the shell rim 30 isindented, so that a tongue 36 is produced to form a second lockingelement. The shell rim 30 is here displaced downward by an amount suchthat the upper surface of the second locking element 36 lies atessentially the same height as the lower surface 19 of the rim 30, whichrests on the seating surfaces 16. Furthermore, the tongue-shaped secondlocking element 36 projects radially beyond the outer edge of the shellrim 30. Thus when the conveyor ball unit has been installed, the tongueshaped second locking element 36 lies between two reinforcing ribs 15and its end projects below the upper surface 11, as shown in FIG. 3.

Opposite to the locking element 36 in the shell rim 30, a slot 39 isprovided . On either side of the slot 39 lies one of the first lockingelements 35. Through this slot 39 a tool, such as the blade of ascrewdriver, can be inserted in order to lever the mounting shell out ofthe supporting structure 10.

The procedure for setting the conveyor ball unit into the supportingstructure is first to tilt the entire unit so that it can be loweredinto the opening 14 with the second locking element 36 down andpositioned between two reinforcing ribs 15. Then the shell rim 30, onthe side of the conveyor ball unit opposite the second locking element36, is pressed down. When strong pressure is applied or the shell rim 30is struck lightly, the first locking elements 35 are deformed in such away that they snap under the upper surface 11, so that the conveyor ballunit becomes firmly seated in the supporting structure 10.

The retaining ring 24 is now stably held on the mounting shell 23because the recesses in which the projections 26 are seated are apposedto the edge of the upper opening 14 and hence have greater resistance todeformation.

To remove the conveyor ball unit from the supporting structure 10, theblade of a screwdriver can be inserted into the slot 39 so that the unitcan be levered out of the opening 14.

The whole arrangement thus comprises only 4 parts. Assuming that themounting balls 22 are considered as a single part, which are all ofsimple construction. Thus, both the disposition of the unit to wear andits price are thereby reduced.

The second embodiment shown in FIGS. 9 to 14 differs from the firstembodiment shown in FIGS. 3 to 8 in the shape of the first lockingelements 35. In the second embodiment, holes are drilled in part of themounting shell 23 between the horizontal portion 25 and the shell rim30. In the region of these holes, the retaining ring 24 is provided withtabs or hooks 27 on one side and with indentations on the other side.The indentations are shaped in such a way that spherical locking pieces35 can be inserted to serve as first locking elements 35, so that eachsphere protrudes for some distance radially out of the hole in themounting shell 23, while its other side is seated in the associatedindentation in the retaining ring 24. The retaining ring 24 is thussecurely held within the mounting shell 23.

To set the conveyor ball unit into a supporting structure 10, oneproceeds as described for the first embodiment. That is, first theconveyor ball unit is tilted and placed in the opening with itstongue-shaped second locking element 36 between two reinforcing ribs 15.Then the conveyor ball unit is tilted back until the spherical firstlocking element 35 is seated on the seating surface 16. Under furtherpressure or a light tap on the shell rim 30, the spherical first lockingelement 35 is pushed inward, owing to elastic deformation of theretaining ring 24 in this area, and snaps under the lower surface of thereinforcing rib 15. In this state, the conveyor ball unit is securelyheld within the supporting structure 10. The retaining ring 24 is alsofirmly held when the conveyor ball unit is in this position because whenthe spherical locking element 35 has been snapped into place under thereinforcing rib 15 it is pressed tightly against the retaining ring 24.

This conveyor ball unit is also of simple construction and comprises asmall number of economically produced parts. Because the processes ofinsertion into and removal from the supporting structure 10 are the sameas for the first embodiment described previously, the second embodimenthas the same advantages.

In the first embodiment described with reference to FIGS. 3 to 8, twopairs of first locking elements 35 and two pairs of projections 26 areshown. It is of course possible to use any number of elements 35 andprojections 26 but it is advantageous for the unit to be symmetrical,especially with respect to the slot 39 and relative to the secondlocking element 36. The same also applies to the second embodiment asdescribed with reference to FIGS. 9 to 14.

What is claimed is:
 1. A conveyor ball unit comprisinga conveyor ball; amounting shell for the conveyor ball; a plurality of mounting balls forsupporting the conveyor ball in the mounting shell; a retaining ring tokeep the conveyor ball in position on the mounting balls within themounting shell; and a first locking element which is inverted into anopening defined by the mounting shell so that it partly projects beyondthe outer surface defined by the mounting shell to attach the mountingshell to a supporting structure and to brace a rim of the mounting shellagainst the supporting structure, and which projects into a radialrecess defined by the retaining ring to fix the retaining ring withinthe mounting shell.
 2. A conveyor ball unit as claimed in claim 1,wherein the first locking element has a spherical shape.
 3. A conveyorball unit as claimed in claim 1, wherein the first locking element canbe releasably snapped fitted into an opening defined by the supportingstructure.
 4. A conveyor ball unit claimed in claim 3 wherein the shellrim defines a slot adjacent to the first locking element, into whichslot a tool can be inserted to lever the conveyor ball unit out of theopening defined by the supporting structure.
 5. A conveyor ball unit asclaimed in claim 4, wherein a pair of the first locking elements areprovided and said slot is located between them.
 6. A conveyor ball unitas claimed in claim 1, wherein at least one second locking element isprovided and forms part of the mounting shell on the other side of theconveyor ball diametrically opposite said first locking element.
 7. Aconveyor ball unit as claimed in claim 1, wherein the mounting shell isformed from a sheet material and defines a part-spherical portion inwhich the conveyor ball is mounted and a substantially horizontalportion running radially outwards from said part-spherical portiontowards said rim of the mounting shell, said substantially horizontalportion being resiliently deformable so that said part-spherical portioncan be moved with respect to said rim.